1. Field of the Invention
The present invention relates to an optical fiber spool, and in particular, to an optical fiber spool and a spool cover for use in storing and transporting an optical fiber.
2. Description of the Related Art
An optical fiber is generally used as an intermediate product for a cable or a completed product in itself. Recently, there has been a drastically increasing demand for optical fibers to establish a superhigh-speed information communications network.
When optical fibers are to come onto the market in the form of cables, they are protected by a multi-protection layer so that their optical and mechanical characteristics can be well maintained. On the other hand, when optical fibers are shipped as a completed product, an additional mechanism should be prepared to maintain their characteristics. As user demand shifts to a long optical fiber, a spool capable of winding a long optical fiber is necessary.
An earlier optical fiber spool has been designed to wind an optical fiber of a short length of about 15-20 km. This spool has a cylindrical barrel and two flanges facing each other with the barrel in between. The spool is easy to handle because the difference between diameters of the barrel and the flanges is narrow, about 83-88 mm, and an optical fiber wound around the spool is lightweight.
However, as user demand shifts to a long optical fiber, the earlier spool has limitations in winding the long optical fiber. Even if a long length of optical fiber is forcedly wound around the spool, end portions of the flanges are warped, thereby collapsing the optical fiber. Especially, the spool is seriously deformed depending on temperature due to the increase in the weight of the optical fiber and difficult to handle. As a result, characteristics of the spool are changed.
The difference between the height of an optical fiber drawing slot and the thickness of a pad brings about several problems including the increase of nonlinearity of the optical fiber. That is, when the optical fiber is drawn through the slot from a shock-absorbing sponge pad, the optical fiber may be caught between the pad and an inner side surface of the flange or forcedly drawn around an auxiliary winding portion, thereby bending the optical fiber. This is a cause of optical fiber failures.
The above problems can be summarized as follows:
(1) it is difficult to wind a long length of optical fiber around the earlier spool because the spool is designed to wind an optical fiber of a 15-20 km length; PA1 (2) the flanges of the spool are warped and the spool is seriously deformed depending on temperature when it is used for a long length winding; PA1 (3) because the optical fiber is non-linear due to the difference between the height of the optical fiber drawing slot and the thickness of the pad, an accurate loss value is difficult to obtain; and PA1 (4) when a long length of optical fiber is wound around the spool, the weight of the spool is increased, causing difficulty in transporting and storing the spool and protecting the optical and mechanical characteristics of the optical fiber from an external environment.
The following patents each disclose features in common with the present invention but do not teach or suggest the specifically recited optical fiber spool and spool cover of the present invention: U.S. Pat. No. 3,650,388 to Osojnak, entitled Tape Canister, U.S. Pat. No. 1,488,322 to Doty, entitled Film Reel Cover, U.S. Pat. No. 1,702,242 to Bureau, entitled Reel, U.S. Pat. No. 4,635,789 to Webb, entitled Locking Mechanism For Magnetic Tape, U.S. Pat. No. 4,974,789 to Milburn, entitled Dispensing Package For A Fiber-Optic Device, U.S. Pat. No. 5,702,066 to Hurst et al., entitled Optical Fiber Spool And Method Of Loading Spool, U.S. Pat. No. 1,981,139 to Bureau, entitled Reel, U.S. Pat. No. 3,391,879 to Le Bus Sr., entitled Non-Crushing Multi-Layer Cable Spooling Method And Apparatus Therefor, and U.S. Pat. No. 2,741,441 to Le Bus Sr., entitled Method And Apparatus Of Cross-Over Cable Spooling.